1. Field of the Invention
This invention relates to a method of measuring heat transfer rate from a surface due to fluid convection, and to apparatus for carrying out said method.
2. Description of the Prior Art
Commonly used methods of measuring rates of heat transfer from surfaces as a result of fluid convection have involved a considerable number of temperature measurements and complex calculations, and it has accordingly been proposed to attach to such a surface a liquid absorbent material whose transmissive or reflective properties for certain radiations vary with the liquid content of the material, wetting the sheet of material with a liquid which evaporates on the passage of the convecting fluid, exposing the sheet to said radiation and to the convecting fluid, and detecting the change in the amount of radiation transmitted through or reflected from the sheet.
In this latter method the variation in the transmission or reflection of the radiation in a given time gives a ready indication of the rate of heat transfer. Such a method is particularly suitable in cases where the convecting fluid is a gas, but it is not so convenient in cases where the heat transfer takes place due to convection in a liquid. In addition, this method can only be used when the surface, from which heat transfer is to be measured, is completely immersed in the convecting liquid.